Vibration isolating system



June 6, 1961 J. M. EVJEN VIBRATION ISOLA'I'ING SYSTEM 2 Sheets-Sheet 1Filed Sept. 21, 1959 V INVENTOR JOHN M. EVJEN H l 5 ATTORNEY Jh'fi 1961J. MIEVJEN 2,987,189

VIBRATION ISOLATING SYSTEM Filed Sept. 21, 1959 2 Sheets-Sheet 2 UnitedStates Patent 1 2,987,189 VBRATION ISOLATIN G SYSTEM John M. Evjen,Louisville, Ky., assignor to General Electric Company, a corporation ofNew York Filed Sept. 21, 1959, Ser. No. 841,104 7 Claims. (Cl. 210364)This invention relates to vibration isolating arrangements, and moreparticularly to suspension systems for isolating the vibrations of themoving system from the frame on which it is supported.

The problem of isolating vibrations of the moving parts of the machinefrom the stationary parts has long been recognized and many solutionshave been proposed therefor. While many of the systems which have beenevolved have been satisfactory, it has been found most dilficult toprovide an arrangement which, together with the elimination ofundesirable vibrations in the supporting framework of the apparatus, isalso economical while at the same time restricting the vibrationalmovement of the apparatus to a reasonable extent. In addition, itfrequently occurs that the moving parts of such apparatus must often beallowed only a certain amplitude of movement and there is thus theproblem of isolating the vibrations of the moving system from the framewhile restraining the motion of the moving system within thepredetermined limits.

As an example of the problems encountered along this line, mostautomatic washing machines of the type presently commercially availablefor domestic use provide a clothes basket in which the clothes arewashed and rinsed, and when it is desired to remove the liquid from theclothes the basket is then rotated at a high speed so as to centrifugethe liquid out of the clothes. Very often the system for effecting thewashing and centrifuging operations does not have its weightsymmetrically distributed about the axis of rotation so that there isinherently an unbalance in the system. In addition, the clothes whichare being laundered most often will not distribute themselves perfectlyabout in the basket but will provide an additional degree of unbalance.There is the further consideration that vibration-caused motion of themoving system must be maintained within reasonable limits, usually onthe basis that the supporting frame or cabinet of the machine must besmall enough to be commercially attractive for home usage. Yet a furtheritem for consideration is that vertical axis washing machines, that is,washing machines of the type which have a basket open at its top whichis reached through a lid in the top of the machine, generally shouldhave a highly limited amount of vertical freedom, both for properfunctioning of the apparatus itself and again because of therestrictions on size inherent in an appliance which is to be used in thespace normally available in most homes. A solution to this problem, inwhich use is made of a system of pulleys with an elongated flexiblemember passing over the pulleys and supporting the moving system on theframe, is disclosed and claimed in application Serial No. 843,611(Bochan) filed concurrently herewith and assigned to the GeneralElectric Company, owner of the present invention.

It is an object of this invention to provide an improved system, basedon the invention of the aforesaid Bochan application, which will be evenmore simple in structure and economical to manufacture than thearrangement of the Bochan application yet which will also in the samemanner effectively prevent the vibrations of the moving system forreaching the stationary part of the apparatus in which the moving systemis included.

As a further object, directed toward apparatus having a particular typeof moving system, it is an object of the invention to provide theimproved vibration eliminating ice suspension system for apparatusincluding components designed to centrifuge.

As a further object directed toward an even more specific structure, Iprovide by my invention an improved vibration isolating suspensionsystem for vertical axis washing machines.

A more specific object of the invention is to provide a vibrationisolating suspension system in which a total of only three pulleys arefastened to the stationary frame of the apparatus and the cable isfastened to the moving system on opposite sides above the center ofgravity of the moving system so as to run over the pulleys between itsends.

In one aspect of my invention, I provide apparatus which includes movingparts and a frame provided for the purpose of supporting the movingparts without receiving the vibrations therefrom. A suspension systemfor securing the moving system on the frame includes an elongatedflexible member which has its ends secured respectively to the movingassembly above the center of gravity and on opposite sides thereof. Thesuspension system also includes first and second pulleys which arerespectively secured on the frame of the apparatus on the twoaforementioned opposite sides of the moving system above the cable ends.A single additional pulley is also secured on the frame with its axis ofrotation so arranged that it rotates in a plane formed by the threepulleys. The cable is arranged to extend from one of its ends first overthe first pulley means, then over the additional pulley, and finallyover the second pulley back to its other end. By means of the additionalpulley the entire system is integrated with only one additional pulleybeing used besides the two pulleys positioned on opposite sides of themoving system.

The features of the invention which I believe to be novel are set forthwith particularity in the appended claims. The invention itself,however, both as to organization and method of operation together withfurther objects and advantages thereof may best be understood byreference to the following detailed description taken in connection withthe accompanying drawings.

In the drawings, FIGURE 1 is a view in perspective, partly broken awayand partly in cross section in order to show details of the invention;

FIGURE 2 is a side elevational view of the machine of FIGURE 1, alsopartly broken away and partly in cross section to show details;

FIGURE 3 is a view in perspective, partly broken away and partly incross section to show details, of my invention used in a different typeof machine from that illustrated in FIGURES 1 and 2; and

FIGURE 4 is a side elevational view, partly broken away and partly incross section, of the machine of FIGURE 3.

Referring now to FIGURES l and 2 of the drawings, I have shown thereinan agitator type vertical axis washing machine 1 having a clothes basket2 which is provided over its entire side wall with perforations 3 andwhich is disposed within an outer imperforate tub or casing 4. Tub 4 ismounted within a frame or outer appearance cabinet 5 which includes abase 6, Vertically extending walls 7 and a top portion 8. In addition,the appearance cabinet may be completed by a separate section 9 seatedon top of portion 8 which in turn supports the control panel 10 providedwith appropriate controls such as 11. Tub 4 is secured to appearancecabinet 5 by any appropriate means such as, for instance, metal straps12 each of which is secured at one end to portion 8 of the frame and atthe other end to the side wall of tub 4. Thus, in effect, the tub formspart of the stationary portion of machine 1, being rigidly secured tothe sta 'a clutch 23 mounted on the motor shaft.

tionary appearance cabinet 5. The upper member 9 is provided with asuitable lid 13 which may be opened so as to provide access to thebasket 2 for insertion and withdrawal of clothes.

At the center of basket 2 there is provided a vertical axisagitator 14which includes a center post 15 and a plurality of suitably formed vanes17. The agitator is further provided with an outwardly and downwardlyflared skirt 18 to which the vanes are joined at their lower ends., Boththe clothes basket 2 and the agitator 14 are rotatably mounted. Thus, asschematically shown in FIGURE 2, the basket is secured to a rotatablemember 19 extending up from within a transmission 20, and the agitatoris mounted on a shaft (not shown) which extends upwardly fromtransmission 20 through member 19 and is joined to center post 15 of theagitator 14 by any suitable means (not shown). During a typical cycle ofoperation of machine 1 liquid is introduced through an inlet 20a; thenthe agitator is oscillated back and forth within basket 2 to wash theclothes. After a predetermined period of this washing action, basket 2is rotated at high speed to extract centrifugally the washing liquidfrom the clothes, the liquid passing through perforations 3 into theouter tub 4 and thence being removed by a suitable pump 21 to a drain.Following this extraction operation, a supply of clean liquid is thenintroduced into the basket for rinsing the clothes as the agitator isthen again oscillated. Finally, the basket is once more rotated at highspeed to extract the rinse Water and discharge it from the clothes sothat it may be removed by pump 21.

Basket 2 and agitator 14 may be driven by any suitable means, as thedrive means form no part of the present invention. However, by way ofexample I have shown them as driven from a reversible motor 22 whichdrives the basket and agitator through a drive including Clutch 23allows the motor to start without load and then picks up the load as itcomes up to speed. A suitable belt 24 transmits power to thetransmission assembly 20 through pulley 25. Thus, depending upon thedirection of motor rotation, pulley 25 of transmission 20 is driven inopposite directions. Transmission 20 is so arranged that it supports anddrives both the agitator drive shaft and the basket mounting member 19.When motor 22 is rotated in one direction the transmission causes theagitator 14 to oscillate within the basket 2. Conversely, when the motor22 is driven in the opposite direction, the transmission drives the washbasket 2 and the agitator 14- together at high speed for centrifugalextraction. While the drive means forms no part of the presentinvention, reference is made to Patent 2,844,225, issued on July 22,1958 to James R. Hubbard et al. and owned by the General ElectricCompany, assignee of the present invention. That patent discloses indetail the structural characteristics of a transmission assemblysuitable for use in the illustrated machine.

Additional structural features which may be noted for more completeunderstanding of the general driving arrangement provided in the washingmachine of FIGURES 1 and 2 include a direct flexible drive 26 from motor22 to pump 21 and a suitable counterweight 27 which, as shown in FIGURE1, is positioned on the opposite side of the rotational axis of thebasket 2 from the motor 22 so that, while there is necessarily somesmall static unbalance resulting from the unsymmetrical structure of thedriving system, it is held to a A further strucural feature to be notedis the provision of a flexible boot member 28 which is secured at itsinner edge to the top of transmission 20 and at its outer edge to thetub 4. This arrangement provides a watertight connection between thetransmission and the tub for retaining water in the tub and basket whileat the same time permitting the relative motion between the tub and thebasket which results from the fact that the basket is part of thesuspended 4 operating system of the machine (as will be more fullydescribed herebelow) and the tub is secured to a stationary frame orappearance cabinet of the machine.

It will be understood that, while the description of the machine thusfar excludes any substantial amount of detail relating to the drive, anddoes not show at all the valves and the particular controls normallyprovided on modern domestic washing machines, the elimination orsimplification of these items is primarily for the purpose of permittinga clear explanation of the inventive concepts set forth below. Inaddition, it will readily be recognized that the omitted details areconventional items in all domestic washing machines, whose structure andpositioning is well known to those skilled in the art.

As previously described, basket 2 is rotated at high speed to effectcentrifugal extraction of the liquid from the clothes in the basket. Ashas also previously been mentioned, the structure of the machine itselfand the arrangement of the clothes in the basket both tend to provideunbalancing forces which, during high speed rotation, cause vibrationinducing forces. These forces result in gyrations of the moving systemwhich includes the basket, transmission, motor, and counterweight. It isimportant that these vibrations be prevented from reaching the frame,that is, the appearance cabinet, in any substantial amount sinceotherwise the machine will have a tendency to move about on the floor onwhich it is located and in fact might well be damaged by suchvibrations.

In order to support the moving system on the stationary frame or cabinet5, I provide a U-shaped flange member 29 rigidly secured at its center30 to transmission 26 so as to form part of the moving system previouslydescribed. Member 29 has a central portion 31 which extendssubstantially horizontally and merges at its ends respectively intosubstantially vertically extending portions 32 and 33. Portions 32 and33 extend upwardly, as shown, on opposite sides of the moving systemoutside tub 4.

A pulley 34 is secured to rotate on a pin 35' fastened in the topportion 8 of frame 5, the pulley being positioned substantially in avertical plane. A second pulley 36 is similarly mounted on a pin 37,also secured in the top portion 8 of frame 5. Pulley 36 is alsopositioned to rotate in a vertical plane. Pulleys 34 and 36 arerespectively located on the same two opposite sides of the moving systemas the upwardy extending portions 32 and 33 of member 29.

A pulley 38 is rotatably mounted on a pin 39 secured to portion 8 offrame 5, and is positioned in a third corner of the frame substantiallyequally distant from pulleys 36 and 34. Pulleys 34 and 36 are bothpositioned so that each one rotates in a plane, preferably vertical asshown, which is tangential to the outer operating surface of the pulley38, i.e., pulley 38 is located substantially at the intersection of theplanes of pulleys 34 and 36. Pulley 38 is mounted to rotate in the planewhich it forms with the outer operating surfaces of the pulleys 36 and34; in the illustrated embodiment the plane is a substantiallyhorizontal one inasmuch as all three pulleys are mounted on portion 8 offrame 5, which portion is in a substantially horizontal plane. It vw'llfurther be seen that the positioning of the third pulley 38 is such thatstraight lines drawn between it and each of the first and second pulleys34 and 36 will be horizontally external to the moving system. Thispermits free unobstructed use of an elongated flexible member, such ascable 40, extending as shown between the'three pulleys so that the cablemay be used without interference resulting from vibrations of the movingsystem.

The cable member generally indicated at 40, has one end 41 securedwithin an opening 42 formed adjacent the upper end of portion 32 ofmember 29. From this point, the cable extends upwardly, passing overpulley 34, and then extends horizontally in the plane formed by thepulleys to pass around the outer surface of pulley 39.

From pulley 39, the cable then extends horizontally to pulley 36,passing over pulley 36 and then down to its other end 43 which issecured in the opening 44 provided adjacent the upper end of portion 33of member 29. The points of engagement of the ends 41 and 43 of thecable with the moving system are, of course, represented by openings 42and 44 in which the cable ends are secured. It is of importance to myinvention that these points be located above the center of gravity ofthe moving system.

As described in the aforementioned Bochan application, the unbalanceforces operating on the moving system when basket 2 is spinning at arelatively high speed cause basically two types of vibrational motion.First, there is a pendulous motion of the system in which it swingsbetween the two pulleys 34 and 36 as though these were fixed points.Since the center of gravity is below the suspension plane where thecable is attached to portions 32 and 33 of member 29, the system isgravity centered and is stable. The second motion is a rocking motion,which occurs about a point, in which one side of the moving system willtend to rise and at the same time the other side of the system will belowered because of the continuous nature of cable 44 and its attachmentto the two opposite sides of the systems. Almost invariably, there is acombination of the two types of motion; however, their causes can tosome extent be separated by stating that single plane unbalances(commonly called static unbalances) cause a predominantly pendulousmotion, whereas a couple (equal unbalances removed 180 circumferentiallyfrom each other and axially separated), also known as a dynamicunbalance, causes a predominantly rocking motion. Thus, the only forceswhich can be transmitted to the frame 5 and to the floor are verticalforces which have very little harmful effect, and a very small amount ofhorizontal force due to the pendnlous or swinging motion between the twopulleys 34 and 36. By far the greater part of the vibrational force ofthe moving system is absorbed by the cable suspension arrangementdescribed and is therefore prevented from being transmitted to frame 5and to the floor on which machine 1 rests. In addition, the fact thatthe cable and pulley arrangement causes one end of the system to risewhen the other end lowers prevents to a substantial extent any verticalmotion of the system which motion, as previously mentioned, is generallynot desired.

In operation, the moving system of machine 1 is so constructed to haverelatively low critical or resonant speeds for both static and dynamicunbalances. At the dynamic unbalance resonant speed, the transmittedframe-vibrating forces are at a peak. Since vibrational forces at thecritical speed increase approximately with the square of that speed, itis highly desirable, in order to keep these forces relatively small,that low critical speeds be provided by proper design of the machine.The design of machines to provide a low static unbalance resonant speedis well known. However, substantial difficulty has been encountered inthe design of a system which will also have the desired low dynamicunbalance resonant speed. The cable suspension system described has beenfound very helpful in this respect in readily permitting a low criticalspeed design to be attained for both types of unbalance. Once the movingsystem is operating above critical speed, the vibratory motion is acombination of a pendulous motion and a rocking motion which areisolated as described above.

It will, of course, be recognized that the extent of motion of themoving system as it passes through the critical speed may be such as torequire damping means, particularly in cases where the system proceedsrelatively slowly through the critical speed and the vibrational forceshave a consequently longer time to operate. While this is not true Wherea high torque power source is available to push the system throughcritical speed quickly, it is not normally economically or practicallyfeasible to pro Vide such a source for domestic washing machines and,

as briefly described above, a more conventional procedure is to providea relatively small motor with clutch means for preventing sudden largetorque requirements. As a result it is desirable in the machinedescribed to provide suitable damping means; while these may take any ofvarious forms, in the present case one preferred construction providesfor four downwardly extending strip members 45, 46, 47 and 48. Strips 45and 47 may be attached, as shown, to the under side of portion 31 ofmember 29, strip 46 is attached to the end of the counterweight 27, andstrip 48 is attached to the moving system on the motor side. Strips 45,46, 47 and 48 are thus secured on the moving system. Arranged incooperative relationship With strip 45 is a frictional damper pad 49biased against the surface of strip 45 by means of a spring 50 securedat its base 5-1 to the base 6 of the machine. A similar damping pad (notshown) engages the other surface of strip 45 and is biased thereagainstby a similar spring 52. It will readily be seen that as the movingsystem goes through its vibrational unbalance caused motion, the pad 49will rub over the surface of strip 45 to provide a damping effect. Inthe same manner, damping assembly 5-3 cooperates with strip 46, dampingassembly 54 with strip 47 and damping assembly 55 with strip 48. Thedamping assemblies associated with the strips 45 and 47 provides dampingin one vertical plane and strips 46 and 48 provide damping in aperpendicular vertical plane, so that essentially uniform damping isprovided for all motions allowed by the system.

It will be seen from the foregoing that a highly effective yeteconomical and simple suspension system is provided by my inventionwhereby a major part of the undesirable vibrations existing as a resultof the operation of the moving system is prevented from reaching theframe of the machine and consequently the base on which the machinestands. In addition, it will be observed that a total of three pulleysand a cable are required to efiect the suspension and vibrationisolating functions, with only a single pulley being required inaddition to the two basically essential pulleys which must be providedon opposite sides of the moving system.

As mentioned in the aforesaid Bochan application, while the constructiondescribed has only two oppositely positioned pulleys 34 and 36, it willreadily be understood that additional pairs of oppositely positionedpulleys may be provided as desired and the system will still beeffective.

Referring now to the use of the same suspension system in a modifiedtype of Washing machine as illustrated in FIGURES 3 and 4, the structurewill be described using like numerals to illustrate like parts. The maindifference between the structure already described and the structure ofFIGURES 3 and 4 is that, in the latter, tub 4 is rigidly secured at thebase to the top of transmission 20 and is not secured to frame 5. Thus,the tub is part of the moving system rather than part of the stationaryframe. As a result, since the tub has the same movement as motor 22, itis stationary with respect thereto and an ordinary shaft 56 may be usedto connect motor 22 to drain pump 21. In addition, the fact that the tubmoves with the transmission 20 and basket 2 means that the lower portion57 of the tub may be rigidly secured to the transmission rather thanrequiring, as in FIGURES 1 and 2, a flexible boot member. Also, becausetub 4 is part of the moving system, it is not necessary to provide as inFIGURES 1 and 2 a member 29; instead, outrigger arms 58 and 59 areprovided on the opposite sides of the moving system secured to andextending from tub 4. At the ends of the outrigger arms 58 and 59 thereare provided openings 60 and 61 to which the two ends 41 and 43 of cable44 are, as before, secured to the moving system at a point substantiallyabove the center of gravity on opposite sides of the system.

In order to show the possibility of various damping arrangementssuitable for use with the general type of washing machine shown, I haveillustrated in FIGURE 3 a damping system wherein members 62 and 63 areprovided with upper horizontal surfaces 64 and 65 respectively. Inaddition, each of the members 62 and 63 has a lower horizontal surface(not shown). In cooperation with surface 64 of member 62 there isprovided a frictional damping pad 66 which is secured to tub 4 andbiased against surface 64 by a spring member 67. A similar damping pad(not shown) is biased against the lower surface of member 62 by a springmember es. A similar damper pad assembly 69 is provided in cooperationwith member 63. It will readily be observed that during the variousrocking and pendulous motions of the moving system the damper padarrangements will move over the horizontal surfaces of members 62 and 63to provide a damping effect on the vibrational movement of the movingsystem. This type of damping system, being closer to the planes in whichunbalances occur, may require less damping force than the type ofdamping system described in FIGURES 1 and 2.

In all other respects the structure of the machine of FIGURES 3 and 4 isthe same as in the machine of FIGURES 1 and 2; both the machines ofFIGURE 1 and of FIGURE 3 use the same suspension system which operatesin precisely the same manner: the cable and pulley arrangement providesfor pendulous motion of the moving system between the two tub pulleys,for rocking motion of the moving system with one outrigger arm going upas the other one goes down, and for the normally occurring combinationsof the two types of movement. In both cases a single additional pulleybesides the two oppositely positioned pulleys is all that is necessaryin order to provide a continuous cable connection from one side of themoving system to the other. The two structures using my invention areprovided to show the ready adaptation of the system to the most commonlyencountered types of vertical axis washing machines, namely, the typewherein the tub is rigidly fastened to the frame and does not form apart of the moving system and the type where the tub is part of themoving system and is separated from the frame.

While in accordance with the patent statutes I have described what atpresent is considered to be the preferred embodiment of my invention, itwill be obvious to those skilled in the art that various changes andmodifications may be made therein without departing from the invention,and I therefore aim in the appended claims to cover all such changes andmodifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A machine comprising a moving system including driving means anddriven means operated at a relatively high speed by said driving means;a rigid frame for said moving system including a base adapted to seat ona supporting surface; and means supporting said moving system on saidn'gid frame so as to prevent any substantial part of any vibrations ofsaid moving system from reaching said frame comprising an elongatedflexiole member having its ends secured respectively to said movingsystem on two opposite sides thereof above the center of gravity of saidmoving system, first and sec- 0nd pulleys secured respectively on saidtwo opposite sides of said moving system above the ends of said flexiblemember, and a third pulley secured on said frame intermediate said firstand second pulleys, said third pulley being positioned so that straightlines drawn between it and each of said first and second pulleys arehorizontally external to said moving system said third pulley beingsecured to said frame to rotate in the plane which it forms with saidfirst and second pulleys, said flexible member extending from one of itsends first up over said first pulley, then in said plane around saidthird pulley, and then in said plane over said second pulley and down toits other end.

2. The apparatus defined in claim 1 wherein said moving system comprisescentrifuging means.

3. The apparatus defined in claim 1 wherein said machine is a laundrymachine and said moving system comprises means for laundering clothesincluding a clothes receiving basket and drive means for rotating saidbasket on a vertical axis at a centrifuging speed.

4. The apparatus defined in claim 1 wherein first damping means issecured on said frame and second damping means is secured to said movingsystem, said first and second damping means engaging each other andforming together a damping system for said machine to limit vibrationalmovement of said moving system as it passes through its critical speed.

5. The apparatus defined in claim 3 wherein said laundering meansfurther includes an imperforate tub member surrounding said basket inwater-retaining relation thereto.

6. The apparatus defined in claim 3 wherein said rigid frame includes animperforate tub member rigidly secured thereto surrounding said basketin water-retaining relation thereto. 7

7. A laundry machine comprising means for laundering clothes including aclothes receiving basket and means for rotating said basket atcentrifuging speed; a rigid frame formed as an enclosing cabinet forsaid laundering means; and means supporting said laundering means onsaid frame so as to prevent a substantial part of any vibrations of saidlaundering means from reaching said cabinet comprising a cable havingits ends secured respectively to said laundering means on two oppositesides thereof above the center of gravity of said laundering means,first and second pulleys secured respectively on said frame on said twoopposite sides of said laundering means above the ends of said cable,said first and second pulleys being secured to said frame to rotate insubstantially vertical planes perpendicular to each other, and a thirdpulley secured on said frame in a common horizontal plane with saidfirst and second pulleys at the intersection of said vertical planes,said cable extending from one of its ends first over said first pulleythen in said horizontal plane over said third pulley, then in saidhorizontal plane to said second pulley, and back down to its other end.

References Cited in the file of this patent

